Grafting culture and fruit development of watermelon (Citrullus lanatus (Thumb.) Matsum. & Nakai) cv. ''Empire No.2''

• Main Authors: Chun-Liang Lin, 林俊良
• Other Authors: Shing-Jy Tsao
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/84375783023209497300

碩士 === 國立臺灣大學 === 園藝學研究所 === 88 === Watermelon (Citrullus lanatus (Thumb.) Matsum. & Nakai) cv. ‘Empire No.2’ was grafted on bottle gourd ‘S-1’, pumpkin ‘Mutual Boom’ and wild watermelon ‘Knight’ to study the effect of temperature on formation of the graft union in a phytotron. All graft combinations showed similar development, including necrotic layer formation in the interface of scion and stock, callus tissues production and proliferation, necrotic layer disruption and dissolution in the order. Then the callus tissues of scion and stock interlocked and vascular tissues connected within grafted plants. The graft union developed more rapidly at temperature of 30/25℃ than at either 25/20℃ or 20/15℃. It took ca. 14 days to develop a successful vascular connection at graft union. But the grafts failed to develop at 15/13℃. All grafted and self-rooted seedlings grew well at 30/25℃ and 25/20℃ and the grafted plants had better growth at 20/15℃ and 15/13℃ than ungrafted ones. The field experiments were conducted for two years to compare the plant vigor and fruit development, among treatments of ‘Empire No.2’ grafted on wild watermelon or bottle gourd or ungrafted. No significant difference was observed in early growth of grafted and ungrafted plants for the first year. All had a vine of more than 200cm in length with 5-6 axillary vines at one month after transplanting. The fruits grew to 35 days after pollination. Total soluble solids content increased up to 28 days after anthesis and remained thereafter. The development of fruit and fruit content was not affected by rootstock. The adverse climate during the early part of the second year experiment inhibited plant growth. However, the growth of grafted plants recovered gradually along with the increasing temperature, but self-rooted plants did not resume growth and died eventually. Following the fruit development, the specific gravity declined and the color of fruit flesh turned red, with a Hunter ‘L’ value starting from 60~40 down to 31~41 and ‘a’ value increasing to 14~17. The total soluble solids content increased to ca. 9 oBrix and vitamin C content of 6 mg/100ml juice. The initial sugars developed in fruit were fructose and glucose which increased and later declined. Sucrose was not measurable in the early stage of fruit growth. Sucrose later increased to 3.2~4.2% and dominated in fruits of first year. Fructose was the major sugar of the fruit with a content of 3-4% in the second year. Grafting culture of watermelon was mainly adopted to serve a normal plant growth and fruit production. Two rootstocks did not give consistent difference in fruit quality.